Defect area management system and method for optical storage medium

ABSTRACT

A defect area management system for an optical storage medium including a management part producing a defect area management signal for real-time processing and transmitting the signal along with data to be written; and a write part executing a defect area management of the optical storage media, writing the data, applied by the defect area management signal from the management part, into the optical storage medium so that whenever a light pickup meets a defect block at the time of writing data requiring the real-time processing into the optical storage medium, it does not have to be moved to the spare area, thus reducing the time it takes to move the light pickup and removing shortcomings of the real-time processing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rewritable optical storage, systemand more particularly to a defect area management system and method foran optical storage medium.

2. Discussion of Related Art

An optical storage media is generally divided into a read only memory(ROM), a write once read many (WORM) memory into which data can bewritten one time, and a rewritable memory into which data can be writtenseveral times. Rewritable optical storage media, i.e. optical discs,include rewritable compact discs (CD-RW) and rewritable digitalversatile discs (DVD-RW, DVD-PAM, DVD+RW)

The operations of writing and playing back data in rewritable opticaldiscs may be repeated. This repeated process alters the ratio of storagelayers or writing data into the optical storage medium from the initialratio. Thus, the optical discs lose its characteristics and generate anerror during recoding/playback. This degradation is indicated as adefect area at the time of formatting, recording on or playing back froman optical storage medium.

Also, the rewritable optical disc may have a defect area due to ascratch on its surface, dirt and dust, or failure during manufacture.Therefore, in order to prevent writing into or reading out of the defectarea, management of such defect areas is necessary.

FIG. 1 shows a defect management area (DMA) in a lead-in area and alead-out area of the optical disc to manage a defect area. Particularly,the data area is divided into groups for the defect area management,where each group is further divided into a user area and a spare area.The user area is where data actually written and the spare area is usedwhen a defect occurs in the user area.

Typically, one disc (e.g. DVD-RAM) has four DMAs, two in the lead-inarea and two in the lead-out area. Since managing defect area isimportant, the same data are held in all four DMAs for data protection.Each DMA includes two blocks and consists of 32 sectors, wherein oneblock consists of 16 sectors. The first-block (DDS/PDL block) of eachDMA includes a disc definition structure (DDS) and a primary defect list(PDL), and the second block (SDL block) include a secondary, defect list(SDL).

More specifically, the PDL represents a primary defect data storagearea, and the SDL represents a secondary defect data storage area. ThePDL stores entries of all defective sectors generated during manufactureand identified during formatting such as initialization orre-initialization. Each entry includes a sector number corresponding toa defective sector and an entry type.

On the other hand, the SDL is arranged by blocks and holds entries ofeither defective areas which may be generated after initialization ordefective areas which cannot be entered in the PDL duringinitialization. Each entry of the SDL includes an area storing thesector number of a first sector of the block having defective sectors,and an area holding the sector number of a first sector of a replacementblock. Defective areas in the data area (i.e., defective sectors ordefective blocks) are replaced with new sectors or blocks, respectivelyby skip defective area technique or linear replacement.

The skip defective area technique is utilized when a defective area orsector is recorded in the PDL. As shown in FIG. 2A, if defective sectorsm and n, corresponding to sectors in the user area, are recorded in thePDL, such defective sectors are skipped to the next available sector. Byreplacing the defective sectors by subsequent sectors, data is writtento a normal sector. As a result, the user area into which data iswritten slips and occupies the spare area in the amount equivalent tothe skipped defective sectors.

The linear replacement is utilized when a defective area or block isrecorded in the SDL. As shown in FIG. 2B, if defective blocks m and n,corresponding to blocks in either the user or spare area, are recordedon the SDL, such defective blocks are replaced by normal blocks in thespare area and the data to be recorded in the defective block arerecorded in an assigned spare area. To achieve the replacement, aphysical sector number (PSN) assigned to a defective block remains,while a logical sector number (LSN) is moved to the replacement blockalong with the data to be recorded. Linear replacement is effective fornon real-time processing of data.

FIG. 3 is a partial diagram of an optical disc recording/playback (R/P)device relating to the write operation. The optical disc (R/P) deviceincludes an optical pickup to write data into and playback data from theoptical disc; a pickup controller transferring or moving the opticalpickup; a data processor either processing and transferring the inputdata to the optical pickup, or receiving and processing the datareproduced through the optical pickup; an interface; and a microprocessor (micom) controlling the components.

Also, a host mans be connected to the interface of the optical disc R/Pdevice to transfer commands and data to and from each other. Such hostcan be any kind of personal computer, and would manage the optical discR/P device. FIG. 4 shows an optical R/P method.

Referring to FIG. 4, if there is data to be written (Step 401), the hostsends both the data to be written and a write command to the opticaldisc R/P device (Step 402). The write command includes a logical blockaddress (LBA) which designates a write position, and a transfer lengthwhich indicates the size of the data to be written.

Upon receiving the data, the optical disc R/P device begins to write thedata into a corresponding LBA of the optical disc (Step 403). Theoptical disc R/P device does not write data into defective areas byutilizing the PDL and SDL, which show defective areas of the opticaldisc. Thus, the write operation is performed by skipping the physicalsector recorded in the PDL or replacing the physical block recorded inthe SDL with an assigned block in the spare area.

When the optical disc R/P device completes writing the received data,the optical disc R/P device informs the host of the completion bytransferring a write completion signal (Step 403). The host thenmonitors whether the write command was well executed (Step 404).Finally, the optical disc R/P device sends (Step 405) a commandexecution report to the host, and the host terminates the data writeoperation on receipt of the report (Step 406).

However, the above conventional technique has several problems. Becauseboth skipping and linear replacement are utilized, when a defectiveblock is found during data write operation, the defective block may bereplaced by an assigned block in the spare area. As a result, theoptical pickup must be transferred to the spare area and retransferredback to the user area in order to continue writing the data. The time totransfer and retransfer the optical pickup may become a significantproblem in a real-time processing.

Therefore, application of the conventional technique described abovewould not be effective when real-time writing is required, such as foraudio-visual (A/V) use, because of its uniform defect area management.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to solve at least theproblems and disadvantages of the related art.

An object of the present invention is to provide a defect areamanagement system with an improved real-time writing for an opticalstorage medium.

Another object of the present invention is to provide a defect areamanagement system and method for an optical storage medium whichgenerates a write command for real-time processing if there is data forreal-time processing and manages defective areas of an optical disc.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

To achieve the objects and in accordance with the purposes of theinvention, as embodied and broadly described herein, a defect areamanagement system for an optical storage medium including a managementunit (or host) producing a defect area management signal for real-timeprocessing and transmitting the signal with data to be written; and awrite unit (or an optical disc R/P device) executing a defect areamanagement of the optical storage media, and writing the data into theoptical storage medium according to the defect area management signal.

In the present invention, the management unit determines whether tooutput a defect area management signal for real-time processing basedupon the input data. The defect area management signal from themanagement unit is a command prohibiting execution of a linearreplacement. Thus, upon receiving the defect area management signal, thewrite unit writes the input data into an optical disc utilizing theskipping replacement.

A method or managing defective areas of an optical storage mediumaccording to the present invention includes producing a defect areamanagement signal for real-time processing and transmitting the signalwith the data to be written, if a real-time processing is required; andexecuting a defect area management of the optical storage medium andwriting the input data into the optical storage medium according to thedefect area management signal.

The defect area management-includes transmitting data to be writtenafter generating a real-time write command;

detecting the volume of data which has not been written during theexecution of the real-time write command based upon receipt orinformation stored in the optical storage medium; and if there is eitherunwritten data or successively connected data, repeating the step ofgenerating the real-time write command to continue writing. The volumeof the unwritten data is detected bay utilizing the information ofdefective blocks which were skipped when writing data into the opticalstorage medium.

The defect area management signal is a command prohibiting an executionof linear replacement. The defect area management signal includesidentification information which indicates real-time data. The step ofwriting the data into the optical storage medium includes writing theinput data according to the real-time write command. If a defectiveblock is found during the writing process, data is written into afollowing normal block, skipping the defective block.

When writing the data is completed, the information of the defectiveblocks skipped during the writing is transferred and stored in theoptical storage medium. The information of the defective blocks skippedto write data on a following normal block during the data writing isrecorded in SDL entries.

According to another embodiment of the present invention, a method ofmanaging defective areas of an optical storage medium with a defectmanagement area includes producing information about the characteristicsof data to be written, and transmitting such information with the datato be written; and executing a defective area management of the opticalstorage medium and writing the input data into the optical storagemedium by using the characteristic information of the data.

The characteristic information of the data includes identificationinformation indicating real-time data, and speed information of theinput data. While data is written into the optical storage medium, if adefective block is found, data is either written into a normal blockfollowing the defective block or written in to a replacement block basedupon the characteristic information of the data.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

The invention will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is a structure of a conventional optical disc in the related art;

FIG. 2A shows a skip defective area technique in the related art;

FIG. 2B shows a linear replacement technique in the related art;

FIG. 3 is a block diagram of a conventional disc R/P device in therelated art;

FIG. 4 is a control sequence of defect area management for an opticaldisc in accordance with the related art;

FIG. 5 is a control sequence of defect area management for an opticaldisc in accordance with the present invention; and

FIG. 6 shows an initialization of a write command for real-timeprocessing in accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. FIG. 5 is the control sequence of defect area management foran optical disc in accordance with the present invention, and shows theoperation of an optical disc R/P device with a host.

To improve real time processing of data, maintaining compatibility withthe conventional command system would be preferable. Accordingly, thepresent invention further adds a data flag for real-time processing tothe conventional command system. As a result, if a defective block isfound during a write command for real-time processing, the defectiveblock is skipped rather than replaced.

FIG. 6 shows a preferred embodiment of the present invention. Generallya conventional write command of 12 bytes for writing data into anoptical disc by skipping defective blocks during writing or playback isaltered in the present invention. More specifically, a reserved area ofthe write command (the 10th byte) includes a flag indicating the type ofdata to be written (Wtype). The reserved area may also includeinformation indicating the speed of the data to be written (Wspeed).Such information would be used by discs which have capability to supportthe flags.

For example, when normal data which does not need real-time writing isinput, Wtype flag is set to 0. However, when data requiring real-timeprocessing is input, Wtype flag is set to 1, thereby informing theoptical disc R/P device that the data requires real-time processing.

Accordingly, if the Wtype flag within the transferred write command isset to 1, the optical disc R/P device skips a defective block duringwriting or playback rather than replacing the defective block. Thus, theinput data is written into a normal block following the defective block.When the input data does not require real-time processing, the Wtypeflag is reset to 0 and the optical disc R/P device allows linearreplacement whereby data is written into the spare area.

Also, the Wspeed flag may be set according to the required write speedof the input data and transferred within the write command. The opticaldisc R/P device determines whether to execute linear replacement byutilizing the Wspeed. Particularly, the speed of data transferred fromthe host to the optical disc R/P device is recorded into the Wspeedarea. The optical disc R/P device then compares the recorded speed ofthe data transfer with the speed by which the data is being written intothe optical disc to determine whether to allow linear replacement.

If the transfer speed of data from the host is close to the writingspeed of the data into the optical disc, execution of linear replacementslows down the writing of data, thereby reducing the speed of datatransfer and increasing the data transfer time. On the other hand, ifthe transfer speed is significantly slower than the writing speed,slowing down the writing of data would not affect the data transfertime. Accordingly, when the transfer speed is lower than the writingspeed by a predetermined amount, linear replacement is executed, exceptwhen real-time processing is required.

The host may determine and control whether to execute linear replacementutilizing the Wtype flag, and/or the optical disc R/P device maydetermine whether to execute linear replacement utilizing both the Wtypeflag and Wspeed.

Referring to FIG. 5, if data to be written in real time, such as digitalTV stream data or camcorder data, is input (Step 501), the hostgenerates a real-time write command and sets the Wtype flag to 1. Thehost then transfers both the data to be written and the write command tothe optical disc R/P device (Step 502) through the interface.

Upon receiving the real-time write command, the optical disc R/P deviceprocesses the transferred data together with the write command, andwrites the data into a designated position (Step 503). The position ofthe optical disc into which the data is written may be designated usingthe LBA or may be specified in advance using another command.

The optical disc R/P device determines whether defective areas existutilizing the PDL and SDL which indicate the defective areas in theoptical disc. If a defective block recorded in the SDL is found duringthe writing of data (Step 504), the optical disc R/P device checks theWtype flag within the write command. Since the write command is forreal-time processing, the Wtype flag would be set to 1.

When the Wtype flag is set to 1, the optical disc R/P device skips thedefective block and writes the data into a normal block following thedefective block (Step 505). Upon completion of writing the data (Step506), the optical disc R/P device sends a report back to the host. Inthe preferred embodiment, if the host requires a current progress duringthe writing of data, the optical disc R/P device transfers the requiredinformation to the host. If there is no request from the host duringwriting of data, the optical disc R/P device sends a report to the hostafter data writing is completed.

Accordingly, if the optical disc R/P device determines that the writingof data is completed, it monitors whether there are any R/P defectiveblocks. A difference exists between the transfer length used by the hostto write the real-time data and the actual size of data to be writtendue to the number of SDL entries skipped during the writing of the data.Thus, if there is at least one skipped defective block, the optical discR/P device indicates an error and transfers the information of skippeddefective blocks to the host (Step 507).

The host monitors whether the optical disc R/P device has appropriatelyexecuted the write command and detects the volume of data which had notbeen written by the real-time write command of Step 502, based upon thereceived report. Namely, the report includes information such as thenumber of defective blocks, i.e. the number of SDL entries, skippedduring the writing.

The host takes into consideration the number of SDL entries in the nextwrite command. Particularly, the host varies the volume of data to bewritten in the next write command, in response to the number of SDLentries skipped during the writing. Because the skipped defective blockscannot be used, the effective size of the disc must be rearranged basedupon the skipped defective blocks (Step 508).

If there is either data which could not be written into the designatedposition of the optical disc due to the skipped defective blocks (Step509) or continuing data successively connected by the real-time writecommand (Step 510), the host returns to Step 502 and repeatstransferring the real-time write command. If there is no further data tobe written or continuing data in Steps 509 and 510, the writing processends.

However, in the preferred embodiment, if there is no further data to bewritten or continuing data, the optical disc R/P device moves to the DMAarea and indicates in the SDL entries where the skipped defective blockswere registered during the recording, that the data corresponding to thedefective blocks has been recorded by skipping the defective blocks.Thus, during playback of the data, the optical pickup need not move tothe spare area, but to the normal block following a defective block whena defective block is found through the SDL.

Furthermore, if Wspeed has been set in the write command when adefective block is found in Step 504, a determination whether to allowand execute a linear replacement for data can be made utilizing Wspeed.Particularly, the optical disc R/P device compares the speed of Wspeedto the actual speed at which the data is being written into the opticaldisc. If a linear replacement would not affect the writing of data, i.e.writing speed faster than the transfer speed, the linear replacement isexecuted and data corresponding to defective blocks are written into areplacement block in the spare area. If a linear replacement woulddetrimentally slow down the writing, i.e. writing speed is slightlyhigher than the transfer speed, a skip defective area technique isexecuted and data corresponding to defective blocks are written intonormal blocks following the defective blocks.

As described above, in the present invention, when data requiring areal-time processing is generated, a real-time write command is sent bywhich a defective block is skipped and the data corresponding to thedefective block is written in a normal block following the defectiveblock. As a result, the optical pickup does not need to move to thespare area whenever a defective block is found, thereby reducing thetime it takes the optical pickup to move to and from the spare area.Thus, the present invention improves a real-time processing of data inthe optical disc R/P device.

The foregoing embodiments are merely exemplary and are not to beconstrued as limiting the present invention. The present teachings canbe readily applied to other types of apparatuses. The description of thepresent invention is intended to be illustrative, and not to limit thescope of the claims. Many alternatives, modifications, and variationswill be apparent to those skilled in the art.

What is claimed is:
 1. A system for storing data on an optical recordingmedium, comprising: a host device; and an optical record and playbackdevice; said host device generating a write command, said write commandincluding Logical Block Address for designating a position to bewritten, a transfer length for indicating an amount of data to bewritten, and a W-type flag for identifying whether real time writing ornon-real time writing is involved, wherein the optical recording andplayback device controls a write operation based on the write commandfrom said host device, and wherein the optical recording and playbackdevice controls the write operation such that a linear replacement for adefective area of optical recording medium is not performed when theW-type flag identifies real time writing, while linear replacement for adefective area is performed when the W-type flag identifies non-realtime writing.
 2. The system according to claim 1, wherein said writecommand further includes W-speed information to determine the writespeed of the input data.
 3. The system according to claim 1, wherein theoptical recording and playback device controls the write operation suchthat a data is not recorded on a defective area and recorded on a nextblock when the W-type flag identifies real time writing, while a data isrecorded on a replacement block of a spare area of the optical recordingmedium when the W-type flag identifies non-real time writing.
 4. Thesystem according to claim 2, wherein the optical recording and playbackdevice determines whether to perform linear replacement into replacementarea of optical recording medium for defective area based on at leastone of W-type flag and W-speed information of write command.
 5. Thesystem according to claim 4, wherein the optical recording and playbackdevice controls the write operation such that linear replacement intoreplacement area of optical recording medium for defective area isperformed when W-speed information indicates an allowable speed forwriting real time data, while linear replacement into replacement areaof optical recording medium for defective area is not performed whenW-speed information does not indicate an allowable speed for writingreal time data, the write operation being performed regardless of thestatus of W-type flag.